Intravascular diseases are commonly treated by relatively non-invasive techniques such as percutaneous transluminal angioplasty (PTA) and percutaneous transluminal coronary angioplasty (PTCA). PTCA is a well-established procedure for dilating stenosed vessel regions within a patient's vasculature. In this procedure, a balloon angioplasty catheter is introduced into the vasculature, typically through an incision in the femoral artery in the groin. The balloon catheter is then advanced through the femoral artery, through the aortic arch, and into the artery to be treated. The balloon portion of the dilation catheter is specifically advanced across the stenosis or constricted vessel, wherein the balloon is inflated. Inflation of the balloon dilates the surrounding vessel and/or displaces the plaque that forms the stenosis. The resulting treated vessel is then characterized by a greater cross-sectional area permitting additional blood flow through the previously occluded or constricted region.
It is not uncommon, however, to have these stenotic lesions form in bifurcated regions of a patient's vasculature. A bifurcation is an area of the vasculature where a first vessel is bifurcated into two or more branched vessels. Stenosis formed within a bifurcation may affect only one of the vessels, or multiple vessels comprising the bifurcated region. Treating the stenosed lesions surrounding a bifurcation can be arduous and ineffective using conventional balloon angioplasty procedures. For example, when the angle between the branch vessels in the bifurcation is small, inflation of the dilation balloon in one branch vessel can cause the ostium of the other branch vessel to collapse. The resulting angioplasty dilation procedure restricts the flow passing through the other branch vessel, thereby decreasing the effectiveness of opening the dilated vessel.
The use of vascular stents, alone or in combination with balloon dilation, is an effective alternative to conventional angioplasty procedures in bifurcated regions. Vascular stents are typically delivered to a stenosed region using a stent delivery catheter. In one common technique, the stent is crimped down into its delivery position over the inflatable balloon. The stent delivery catheter is then advanced to the lesion site under any suitable, known visualization technique. Once positioned across the stenosed lesion, the balloon of the catheter is radially expanded. The radial expansion of the balloon causes the struts of the stent to bend and to likewise expand the stent to engage the surrounding vascular wall. Once properly seated within the vessel wall, the frame of the stent opposes inward radial forces associated with vessel rebounding.
There are three basic types of intravascular catheters for use in such stent delivery procedures including fixed-wire (FW) catheters, over-the-wire (OTW) catheters and single-operator-exchange (SOE) catheters. The general construction and use of FW, OTW and SOE catheters are all well known in the art. An example of an OTW catheter may be found in commonly assigned U.S. Pat. No. 5,047,045 to Arney et al. An example of an SOE balloon catheter is disclosed in commonly assigned U.S. Pat. No. 5,156,594 to Keith.
While there have recently been considerable advances in stent design and stent deployment techniques, deployment of stents in the treatment of bifurcated lesions remains problematic, particularly where both downstream branch vessels are affected by the lesion. Current techniques of dealing with such lesions typically require the deployment of a slotted tube stent across the bifurcation. Once the first stent is deployed, the treating physician must then advance a dilation balloon between the struts of the stent already deployed in order to dilate the second branch vessel. The physician may then attempt to maneuver a second stent through the struts of the stent already deployed, into the second branch vessel for deployment. This presents significant difficulties. For example, dilating between the struts of the stent already deployed tends to distort the first stent. Numerous recent innovations in both stent designs and stent delivery catheter designs have allowed physicians to overcome these procedural difficulties.
International Application No. PCT/US99/20085 filed on Sep. 2, 1999 (hereinafter referred to as Intl. App. 99/20085), and incorporated herein by reference, discloses a system for delivering bifurcation stents. The stent deployment system includes a tubular member having a first and second end and a generally longitudinal opening between the first and second ends. The tubular member has an inner periphery sized to receive a stent therein. A plurality of apertures are disposed on opposite sides of the generally longitudinal opening. An elongate retainer is removably receivable within the apertures to retain the stent in the tubular member and to release the stent from the tubular member when removed from the apertures.
International Application No. PCT/US99/03988 filed on Feb. 24, 1999 (hereinafter referred to as Intl. App. 99/03988), and incorporated herein by reference, discloses a dilation and stent delivery system for bifurcated lesions. The stent delivery device disclosed includes a pair of dilation balloons. Each dilation balloon is coupled to a balloon catheter that is fitted within a sheath. When advanced through the tortuous vasculature of the patient, each of the dilation balloons of the stent delivery device tracks over its own guidewire, one guidewire being disposed in each branch vessel of the bifurcation.
Both of the stent delivery systems disclosed above include the use of multiple wire members in order to effect their respective stent delivery procedures. Identifying and managing numerous wire members adds unnecessary strain to a physician during a medical procedure. Due to the size, the commonality; and the shear number of wire members used, it is easy for a physician and his/her staff to be confused and delayed with the important task of wire management. Additionally, physicians painstakingly advance and withdraw these wire members within a patient's body until they are properly positioned. Once properly positioned, a physician desires to secure these wire members to insure they do not later shift. A minor shift in a wire member's placement can easily negate all of the physician's prior efforts.